Regional Green Building Case Study: Year Two Report

Illinois Clean Energy Community Foundation

The Regional Green Building Case Study Project is funded through the generous support of the Grand Victoria Foundation and the Illinois Clean Energy Community Foundation and is a collaborative, multi-year research study between the U.S. Green Building Council-Illinois Chapter, the City of Chicago, EPA Region 5, Delta Institute, and the Center for Neighborhood Technology (CNT).

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Based on the success of the first year of the Regional Green Building Case Study Project and with generous support from the Grand Victoria Foundation and the Illinois Clean Energy Community Foundation, this unique research project grew to include 51 projects in 2010. The first year report of the study was released during the fall of 2009. The Regional Green Building Case Study: Year Two Report was released in September, 2011.

An analysis of 51 LEED-certified green projects in Illinois found that most—specifically those that prioritized energy efficiency during the design and construction phase—use less energy than a typical commercial building. The study also showed that additional costs associated with green construction varied across projects, with a median value of $3.81 per square foot. In addition, building occupants are generally satisfied with their work environment and the commute to these LEED® projects.

“Not all green buildings are alike when it comes to energy efficiency,” said Anne Evens, director of the nonprofit CNT Energy, which conducted the study in partnership with the U.S. Green Building Council – Illinois Chapter (USGBC – Illinois). “Maximizing efficiency requires starting with the right priorities, monitoring usage, and tweaking operations and maintenance over the life of a building. Buildings account for a large portion of our global warming emissions here in Chicago, and building owners need to be diligent about efficiency to reduce emissions and save on utility bills.”

The study, “Regional Green Building Case Study: Year Two Report,” is a follow-up to a 2009 study that examined the energy usage and other environmental factors in 25 LEED-certified buildings in Illinois. Of the 51 buildings in this report, 19 also participated in 2009. To receive LEED (Leadership in Energy and Environmental Design) certification, the U.S. Green Building Council rates green building projects on a point system for features that improve energy efficiency, indoor air quality, water use, and other areas. CNT Energy analyzed how projects performed over multiple years in areas including energy and water use, greenhouse gas emissions, operating costs, commute transportation and occupant comfort.

The participating green building projects include offices, museums, police stations and other building use types. The study’s sample represents nearly 25 percent of the state’s LEED-certified projects and includes projects from throughout the Chicago metropolitan area and central Illinois. The projects vary in size from 971 square feet to 4.2 million square feet. All provided at least 12 months of post-occupancy energy utility data. Most were able to provide energy use information for entire buildings, while 16 were able to provide only partial information about energy usage.

According to the U.S. Energy Information Agency, the average energy use intensity (EUI) for commercial buildings in the Midwest is 99 kilo-Btu per square feet per year (kBtu/ft2/year). Sixty-four percent of the LEED projects that provided energy use data for the entire building used less energy than this average for commercial buildings. Likewise, 77 percent of projects that provided partial energy use data performed better than a similar benchmark.

Twenty three participants provided information on a “green premium,” which is the difference between a project’s actual construction costs and the expected costs had the project been completed without green features. Two projects reported no green premium, while the others reported premiums ranging from less than $1 per square foot to $107 per square foot. Most projects noted that grants or other financial incentives helped to offset the green premium.

Of the 19 study participants that provided information on operating costs, 11 indicated that their costs were lower than before moving into a green building, five noted no change in costs, two reported that they were not tracking such information, and one reported that costs had increased.

“Sustainability efforts should not stop after the design and construction phase,” said Doug Widener, executive director of USGBC – Illinois. “Achieving ideal performance for green buildings requires understanding how the building performs in the first place and continuously monitoring how it performs over time.”

The USGBC – Illinois Chapter presented these findings, along with other other contributors, at Greenbuild 2011.